#队列：先进先出
import collections


queue = collections.deque()
print(queue)

#进队
queue.append("A")
print(queue)
queue.append("B")
print(queue)
queue.append("C")
print(queue)


#出队（取数据）
res1 = queue.popleft()
print("res1 =",res1)
print(queue)
res2 = queue.popleft()
print("res2 =",res2)
print(queue)
res3 = queue.popleft()
print("res3 =",res3)
print(queue)